The present invention relates to an image-resolution conversion apparatus for converting image data items having different pixel densities, supplied from image data-output devices such as a personal computer and a facsimile system, so as to match the pixel density of a particular printer system, and to a printer system including the above image-resolution conversion apparatus.
Printer systems capable of printing image data (e.g, graphic data) in addition to character data have become popular and widely used. Printer systems of this type, which have high printing resolution (pixel density) and can print information on normal paper, include an electrophotographic printer system having a laser or a light-emitting diode (LED) as a light source, a thermal transfer printer using a heat-sensitive head, and an ink-jet printer. The resolution of these various printers ranges from 200 to 480 dots/inch. The normal arrangement in this type of printer system is to employ a main scanning resolution and a subscanning resolution.
The resolution of output images differ from that in image data-output devices, such as personal computers and wordprocessors. For this reason, when a printer having a higher resolution than that of the image data-output device is used, the performance of the printer cannot be utilized to the maximum. In the worst case, some systems fail to allow connection between the printer and the image data-output device
The conventional printer system for connection to an image information output device such as a personal computer or a wordprocessor must have a resolution which matches that of the image data-output device. If a user wishes to use a plurality of image data-output devices having different resolutions, a plurality of corresponding printer systems are required, thus resulting in high-cost system configurations.
In a G III mode facsimile system, used as an image data-output device, the pixel density of an image along the main scanning direction differs from that along the subscanning direction. Consequently, it is difficult for a conventional printer system to appropriately print image data received from such a facsimile system.